Question

A cargo plane flew from the US across the Atlantic at 212 mph, and flew back to the US at 232 mph. Given that the first trip took 2 hours longer, how long was the return trip

Answer 1

Time taken for return trip = 2 hours 12 minutes

Explanation:

1st trip: fly from the US across the Atlantic

2nd trip: fly back to US (return trip)

Let time taken for 2nd trip be =
`t` hours

Given: The first trip took 2 hours longer

Time taken first trip =
`(t+2)` hours

Speed for 1st trip = 212 mph

Speed for 2nd trip = 232 mph

Distance =
`Speed* time`

Distance for 1st trip =
`212* (t+2)= (212\ t+424)` miles

Distance for 2nd trip =
`232* t= 232\ t` miles

We know that the distance is same for both trip as the cargo plane is going and returning back the same distance.

So,

`232t=212t+424`

subtracting both sides by
`212t`

`232t-212t=212t+424-212t`

`20t=424`

Dividing both sides by 20.

`(20t)/(20)=(424)/(20)`

∴
`t=21.2` hours

`t=21\ hours\ and\ 12\ minutes`

`[As\ 0.2\ hours\ =(0.2* 60)\ minutes=12\ minutes]`

Time taken for return trip = 2 hours 12 minutes